The Image reconstruction is an important problem in optical tomography. The process of the image processing requires the study of photon migration in biological tissue. There are several approaches to study and simulate propagation of photons in biological tissues. These approaches are categorized into stochastic and analytical groups. The Monte Carlo method as a stochastic method is widely used to simulate the propagation of photons in biological tissues which is time consuming. In other hand, the diffuse equation can be also applied to simulate the migration of photons in tissues. In this study, a solution to diffuse equation based on green theorem is applied to study the diffusion of photon in biological tissue. The precision and accuracy of this presented method is evaluated by comparing with Monte Carlo method and experimental Data.